Vented stretch films are well known and such films are commonly employed, for example, to wrap goods and products of various types positioned on a pallet, the film wholly or partially covering the goods or products and also typically applied to the pallet itself to secure the pallet to the items positioned thereon. Vents in the nature of preformed openings in the film provide air circulation, the films themselves typically being polyethylene, although other stretch film sheet materials can be employed as well.
U.S. Patent Application Publication No. US 2005/0123721, published Jun. 9, 2005, illustrates a stretch film for the packing of goods, particularly for the packing of goods stacked on a pallet, the stretch film comprising a prestretched main film reinforced by reinforcement strips extending in the longitudinal direction. The reinforcement strips are made from film strips of prestretched film which have been folded a plurality of times in the longitudinal direction. Two mutually staggered rolls of preformed holes are formed in the main film between adjacent reinforcement strips. The holes are formed in the main film by perforating rollers, one roller having cylindrical protrusions and the other roller having cylindrical recesses of corresponding shape. One or both of the perforating rollers are heated so that the holes are molded into the main film and not generated by punching. Alternatively, a single perforating roller with protrusions may be utilized to form holes. The holes may be round, oval or elliptic shape.
U.S. Patent Application Publication No. US2008/0280098, filed Nov. 13, 2008, discloses a stretch film comprising a base film made of a stretchable plastic film material, a multiplicity of holes in the base film arranged in several columns along a main direction, and at least one reinforcement strip made of a stretchable plastic film material. The reinforcement strip is arranged and fixed on the base film in an area between two adjacent columns of holes. The thickness of the base film is greater than or equal to the thickness of the reinforcement strip and the width of the reinforcement strip is as great as possible, but is such that the reinforcement strip does not contact or overlap the holes in the adjacent columns of holes. The reinforcement strip may be fixed to the base film so as to be inseparable and indistinguishable from the base film.